E. De Stefani classifies this surname as a Friulian microtoponymic, derived from the dialectal word bearc', a properly Friulian term designating a "grassy and enclosed piece of land adjacent to the house", of old Germanic origin, which over time became a surname. The surname is documented in Friuli at least from the mid-16th century, with spellings such as di bayarzo, à Baiartio, di Bajarzio, da baiarzo and Bearzi, which reflect the graphic oscillation peculiar to Friulian.

According to De Stefani, in the Carnia —a mountainous area of northern Friuli— the surname is concentrated especially in Oltris (a hamlet of Ampezzo), Tolmezzo, Prato Carnico, Enemonzo and hamlets of Socchieve. The truncated form Bearz is attested in Aiello del Friuli. On the same root, variants with different suffixes are recorded: Bearzot, Bearzotti, Bearzatto and Bearzatti, distributed in localities of the provinces of Udine and Pordenone.

E. Rossoni agrees on the dialectal origin, although he identifies the word as beàrz and specifies its Ostrogothic filiation —rather than old Germanic in a broad sense—, meaning "enclosure, fenced land". Rossoni also adds a second hypothesis: a possible derivation from the place name Biarzo, a locality situated in the Natisone valleys, in the province of Udine.